Method and apparatus for securing vibrato effects



A. C. YOUNG June 28, 1966 2 Sheets-Sheet 1 Filed June 18, 1962 INVENTOR:

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METHOD AND APPARATUS FOR SECURING VIBRATO EFFECTS June 28, 1966 2 Sheets-Sheet 2 Filed June 18, 1962 Aik 4 @22 5 5% r0 DELAY LINE United States Patent 3 258 519 METHOD AND APPARATUS FOR SECURING VIBRATO EFFECTS Alan C. Young, Park Ridge, Ill., assignor to Hammond Organ Company, Chicago, Ill., a corporation of Delaware Filed June 18, 1962, Ser. No. 203,068 2 Claims. (Cl. 841.25)

This invention relates in general to an arrangement for creating a vibrato effect in an electrical musical instrument such as an organ and more particularly to arrangements and methods for producing a vibrato in a more versatile and economical manner.

The objects of the invention therefore include an improved arrangement for securing an improved vibrato-r effect in an electronic organ. Basically this is achieved in a novel and unique manner by mismatching the terminations of a standard delay line such as used for creating the ordinary vibrato effect to create electrical reflections in the line which are detected in response to a scanning action. The effect created thereby will generally be referred to as a vibrato celeste.

- Other objects of the invention include an improved scanning arrangement for a vibrato delay line in order to provide'certain advantages over the capacitative type scanning arrangement presently in use as typified by the concept disclosed in Patent No. 2,905,040, issued to Hanert on September 22, 1959.

Still another object of the invention is to provide an arrangement in which tone signals are introduced into both ends of .a vibrato delay line of a type similar to that described in the aforementioned patent for the purpose of creating a wide range of musical effects including the vibrato celeste effect mentioned above.

Yet another object of the present invention is to provide an improved and unique arrangement for controlling the percentage shift in frequency of a tone signal to which a vibrato is introduced whereby the vibrato is maintained substantially constant over a wide tone signal frequency range. This is achieved by a shift in the phase of a tone signal in a series of steps with the amount of the shift controlled by a non-linear frequency responsive circuit having a photocell therein whose resistance is controlled by an associated lamp so that a substantially constant percent of shift is achieved.

The manner in which the above objects are accomplished together with others will become apparent on examination of the following specification and claims in conjunction with the drawings, wherein:

FIG. 1 illustrates the pertinent circuit portions of a delay line arrangement for use in an organ to secure a vibrato celeste effect;

FIG. 2 illustrates one arrangement utilizing the improved scanning concept of the present invention;

FIG. 3 illustrates a plurality of cascaded phase shift circuits utilizing photocell-s for securing a substantially constant vibrato; and

FIG. 4 illustrates another arrangement for using a delay line in an organ to secure vibrato effects.

In FIG. 1, there is illustrated a pair of leads and 12 respectively to which tone signals are supplied under control of the upper and lower manual keyboard respectively, for example, of an organ. A pair of switches 14 and 16 respectively enable the tone signals on leads 10 and 12 to be applied either to a conventional amplifier 18 for application to an output system 20 or to a vibrato channel 22.

The vibrato channel 22 feeds an amplifier tube 24 through a resistor R1 and the amplifier in turn feeds a cathode follower 26. A resistance capacitance mesh Patented June 28, 1966 "Ice comprising the capacitors C1 and C2 together with resistors R2, R3 and R4 extends a degenerative signal from the cathode of cathode follower 26 to the input of tube 24. The output of the cathode follower 26 is extended through a blocking capacitor C3 and a voltage dropping resistor R5 to the input terminal of a vibrato delay line 30.

The line 30 comprises a group of serially connected inductances or coils L-LX terminating in a resistancenetw-ork 31. Respective terminals of the coils J-JX are connected by means of a respective capacitance C-CX to a common lead 32. Respective junctures J-JX are also connected to respective terminals of a capacitative scanning device 34. The device 34 has a scanning arm 36 which is connected to the output system 20 and it is rotated to sense the voltage appearing at the respective junctions J-JX for application to the output system 20, as explained in the aforementioned patent.

A group of manually controlled switches 38-44 are provided for selectively interconnecting respective ones of the junctions J-JX with different terminals of the scanning device 34 in order to vary the amount of vibrato by controlling the total number of junctions scanned by device 34.

A vibrato chorus effect is provided on operation of a switch which disconnects a shunt on a resistor R6 tied to the delay line so that the scanning arm 36 also senses the original signal in its periodic scanning to apply the same to the output system 20 in conjunction with the phase shifted outputs of the delay line.

The resistance network 31 is connected between the termination junction IX and the lead 32. It comprises a pair of shunt resistors R7 and R8 which provide a normally balanced termination for the line. These resistors R7 and R8 are connected in series with resistors R9 and R10 each shun-ted by a respective switch 46 and 47. Switches 46 and 47 when operated to their open position remove the respective shunt on the associated resistors R9 and R10 to place the respective resist-or in series with resistors R7 and R8 and thereby unbalance the termination of the delay line 30.

The result is that the signals being transmitted over the delay line are then reflected back over the delay line to create additional phase shifts and/or in addition give rise to beats and nulls as the signals are either reinforced or cancelled. The scanner 34 detects these conditions which give rise to the unusual and interesting vibrato celeste effect. The effect of course is varied depending on which of the switches 46 and 47 is operated since the respective resistors R9 and R10 are of considerably different value.

Each switch 46 and 47 also has a respective switch 48 and 49 associated therewith for the purpose of connecting a respective compensating resistor R11 or R12 between the lead 32 and the input to the delay line 30.

In FIG. 2, there will be seen a variation of the scanning and output system seen in FIG. 1. In this case the scanning device 34 is replaced by a group of photocells 50 arranged in respective groups 52, 54 and 56, for example, each feeding a respective output system 58, and 62.

Each cell 50 is fed from a respective junction of a delay line such as shown in FIG. 1, as indicated by leads I to IX, so that when the cells are scanned by a cyclical light source at a vibrato rate in any well known manner, each will pass a signal corresponding to that at the respective junction of the delay line. With this system it is possible to scan the line and transmit the output to respective speakers having different formants indicated by the output systems 58, 60 and 6-2 in a sequence phased with the scanning cycle and thereby shift the formant as desired. If desired, of course, the output of the cells may be connected to a single output system as indicated by the broken lines X and Y.

The arrangement shown in FIG. 3 comprises a series of cascaded phase shift circuits 63, 64 and 66 for securing a vibrato effect. Each circuit includes a tube 68 having a capacitor Ca connected between its plate and a respective photo-resistive element P arranged in shunt with a resistor R611 and connected to the respective cathode through a capacitor Cal. The junction of the respective photocells P and the capacitor Ca is connected to the grid of the tube in the succeeding stage and the output of the last stage 66 is connected to an amplifier 69 whereafter the signal is applied to an output lead 69'.

Since the voltage between the plate and cathode of each tube 68 is substantially 180 out of phase, the voltage at the grid of the tube in the succeeding stage is dependent on the reactance of the capacitor Ca at any particular frequency and the resistance of the photocells P. To vary the resistance of the photocells P, a light source 70' is provided and a mask 72 driven by a motor 74 is interposed between the light source 70' and the phot-ocells for cyclically varying the photocell resistance at a vibrato rate.

Thus an input signal applied from a lead 76 to the grid of the tube 68 in the first stage is phase shifted by an amount dependent on the resistance of the photocells P at any particular instance and the reactance of the capacitor Ca. Since these values may be balanced for a desired shift, a substantially constant percent of vibrato may be secured over most of the tone frequency spectrum.

The arrangement shown in FIG. 4 comprises a delay line 80 which includes a series of coils La-Lax with the junctions being connected through capacitors Cb-Cbx to a common lead 81. The junctures are scanned by a scanning device 82 for supplying a vibrato signal effect on lead 84 in a manner similar to that explained in the aforementioned patent or in connection with FIG. 1. If desired, the scanning arrangement shown in FIG. 2 may be utilized in an obvious manner. In any event the delay line 80 is fed at its opposite ends from respective signal sources A and B through respective resistors Rc. Resistors Rd, which are of lower resistance value than resistors Re, are provided in order to terminate the line for preventing signal reflections at either end of the line.

The signal sources A and B may actually be intermediate amplifiers fed from a common signal source and may supply the same or different signals into the opposite ends of the line 80. If the signals are the same, a considerable reinforcement or cancellation usually occurs at certain stages in the line 80 and thereby a very unique vibrato effect similar in some respects to that explained for FIG. 1 is achieved. Or in the case where differing signals are fed into opposite ends of the delay line, the resultant phase shift at each junction will of course represent a composite effect which is of another character from that where similar signals are used, but it still creates a most unique musical effect.

The foregoing constitutes a description of various improvements in arrangements for securing a vibrato in a musical instrument which are capable of numerous modifications and whose limitations are believe-d more adequately set forth in the following claims.

I claim:

1. An arrangement for securing a virbrato in a musical instrument, the improvement comprising a delay line including a group of serially connected coils and a capacitor connected between each juncture and a common lead whereby an input signal connected to a first one of said coils is shifted in phase on transmission through said coils, an arrangement for cyclically scanning respective junctures at a vibrato rate for detecting a signal of shifted phase at the respective junctures, and a termination impedance connected between a last coil in said group and said common lead, said termination impedance having a value to balance said line to avoid signal reflections at the end of said line, additional termination impedance having a value when connected to the last said coil in said group to unbalance said line to produce signal reflection at the end of said line, and switch means for connecting or disconnecting said additional termination impedance at the will of the operator.

2. An arrangement for securing a vibrato in a musical instrument, the improvement comprising a delay line including a group of serially connected coils and a capacitor connected between each juncture and a common lead whereby an input signal connected to a first one of said coils is shifted in phase on transmission through said coils, an arrangement for cyclically scanning respective junctures at a vibrato rate for detecting a signal of shifted phase at the respective junctures, at least three termination impedances, switch means for connecting a selected one of said termination impedances between a last said coil in said group and said common lead, one of said impedances when so connected producing a balanced line so as to avoid signal reflections at the end of said line, a second of said impedances when so connected unbalancing said line to create reflected signals for detection by said scanning arrangement, and a third of said impedances when so connected unbalancing said line more than the second of said impedances when so connected.

References Cited by the Examiner UNITED STATES PATENTS 2,382,413 8/1945 Hanert. 2,509,923 5/1950 Hanert. 2,523,222 9/1950 Marks. 2,551,802 5/1951 Kreithen. 2,905,040 9/1959 Hanert 841.20 3,054,973 9/196'2 Adams.

ARTHUR GAUSS, Primary Examiner.

E. DREYFUS, Assistant Examiner. 

1. AN ARRANGEMENT FOR SECURING A VIRBRATO IN A MUSICAL INSTRUMENT, THE IMPROVEMENT COMPRISING A DELAY LINE INCLUDING A GROUP OF SERIALLY CONNECTED COILS AND A CAPACITOR CONNECTED BETWEEN EACH JUNCTURE AND A COMMON LEAD WHEREBY AN INPUT SIGNAL CONNECTED TO A FIRST ONE OF SAID COILS IS SHIFTED IN PHASE ON TRANSMISSION THROUGH SAID COILS, AN ARRANGEMENT FOR CYCLICALLY SCANNING RESPECTIVE JUNCTURES AT A VIBRATO RATE FOR DETECTING A SIGNAL OF SHIFTED PHASE AT THE RESPECTIVE JUNCTURES, AND A TERMINATION IMPEDANCE CONNECTED BETWEEN A LAST COIL IN SAID GROUP AND SAID COMMON LEAD, SAID TERMINATION IMPEDANCE HAVING A VALUE TO BALANCE SAID LINE TO AVOID SIGNAL REFLECTIONS AT THE END OF SAID LINE, ADDITIONAL TERMINATION IMPEDANCE HAVING A VALUE WHEN CONNECTED TO THE LAST SAID COIL IN SAID GROUP TO UNBALANCE SAID LINE TO PRODUCE SIGNAL REFLECTION AT THE END OF SAID LINE, AND SWITCH MEANS FOR CONNECTING OR DISCONNECTING SAID ADDITIONAL TERMINATION IMPEDANCE AT THE WILL OF THE OPERATOR. 